Actually there is still much left to find out. Like which C'Tan is the machine god, is it the Dragon like some think, or is it some other one? Also what about the weapons the Eldar use to have that could destroy a C'Tan that have been hidden? The Deciver may think he has hidden them beyond thier reach, but they are still in the materium, and its been a long while since the C'Tan have been around, and alot of exploring has been done. For instance what is the ancient artifact that was found by the Space Marines (explained in the Eldar codex), it could be one of these weapons, and its in the hands of the Impire now. So who knows. There are other things going on that need to be explained but I have rambled on long enough.